Following our post on April 21st , some of 3DXPlorer users wrote to us to ask how to create their own quality images , to be used with the « open sky » scene.

You can find several methods and even tools to automatically generate spherical or hemispherical images. Some of them are quite complex though. We wanted to share a simple method here , which is sufficient for many of your projects.

You can find easily, a royalty free image, thatyou like. But these images are usually of low resolution, and not spherical. Take one of those low resolution images, like the one below:

Resolution: 512 x 256

Crop the image in a way that the bottom line fits with the ground surface of the landscape, perfectly horizontal, and that the sky is as high as possible. Duplicate and mirror this surface, and juxtapose the copy on the same side as the axis of symmetry used for mirroring the original image. You’ll obtain this:

Resolution: 1024 x 256

If you need a higher resolution, you can repeat this operation once again :

Resolution: 2048 x 512

Through this simple method, you can « generate » quality pixels, by using the image’s own pixels ! The result is a cylindrical image (the two extreme lines join smoothly, thanks to the symmetry).

But in some scenes like the « open sky » , they can be used instead of a hemispherical one, if the buildings are not too high, thanks to the big size of the whole scene, the vertical deformation is not perceptible.